1,2,3,2,4,5,6,7,8,1- 1Hydrology and Quantitative Water Management Group, Wageningen University, Wageningen, The Netherlands
- 2Meteorology and Air Quality Section, Wageningen University, Wageningen, Netherlands
- 3Institute for Water and Environment, Karlsruhe Institute for Technology, Karlsruhe, Germany
- 4Department of Meteorology, University of Reading, Reading, United Kingdom
- 5ARC Centre of Excellence for Climate Systems Science, University of New South Wales, Sydney, Australia
- 6Chair of Climatology, Technische Universität Berlin, Berlin, Germany
- 7Geoinformation in Environmental Planning Lab, Department of Landscape Architecture and Environmental Planning, Technische Universität Berlin, Berlin, Germany
- 8Department of Environmental Meteorology, Institute for Landscape Architecture and Landscape Planning, University of Kassel, Kassel, Germany
The urban surface interacts differently with the overlying atmosphere compared to natural surfaces, resulting in phenomena such as the urban heat island and the urban breeze. Water availability is a key factor governing the energy exchange between the surface and the atmosphere. Evaporation diverts energy from heating the air and requires both energy and water. However, few studies explicitly focus on this coupling between the surface energy and water balance.
Here, both observations and models are used to explore how water influences the urban climate by bridging these balances. Water storage serves as the source of evaporation during dry periods, but estimating its capacity is challenging due to its fragmented nature. Eddy-covariance observations from 14 cities reveal the recession after rainfall, providing insights into how much water is stored. Water storage capacity appears to be significantly lower in cities than in natural areas.
Focusing on a single city, we link neighborhood-scale evaporation dynamics to patch-scale observations and conceptual models. Eddy-covariance footprint modeling enables this connection by accounting for the dynamic surface cover composition. Large-eddy simulations demonstrate that this composition is highly sensitive to the location of the eddy-covariance measurements. These same observations are often used to evaluate urban land surface models. Despite the inherent link between the water and energy balance, urban land surface models do not simulate evaporation more accurately when they include improved water balance representations. This discrepancy may be explained by human modeling error or differences in model components beyond the water balance. Enhancing the water balance could involve ensuring water balance closure and revising the runoff parameterization.
As water is directly relevant to the urban climate, urban water management must consider its effects on energy exchange. This knowledge has the potential to contribute to the creation of more livable cities.
How to cite: Jongen, H., Steeneveld, G.-J., Grimmond, S., Lipson, M., Meier, F., Vulova, S., and Teuling, R.: Bridging balances: water and energy in the urban climate, 12th International Conference on Urban Climate, Rotterdam, The Netherlands, 7–11 Jul 2025, ICUC12-36, https://doi.org/10.5194/icuc12-36, 2025.
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